1. Field of the Invention
This invention relates to micro-conductors and more specifically to a method of fabricating customized micro-conductors.
2. Description of the Related Art
Microelectronic fabrication techniques are used to electrically connect integrated circuits (ICs) to the terminals of the electronic packages on which they are mounted.
The most common technique used is "wire bonding", in which fine aluminum or gold wires are used to make electrical contact between the metallized pads of an integrated circuit (IC) and the electronic terminals of the package. The wires are bonded one at a time, with each wire requiring two bonds (one at the IC and the other at the electronic terminal). Wire bonding techniques include thermocompression bonding, ultrasonic bonding and thermosonic bonding and are discussed in D. V. Morgan and K. Board, An Introduction to Semiconductor Microtechnology (Second Edition), John Wiley & Sons, Chichester (1990), pages 111-114.
In some microelectronic device structures, the wire bonding method does not provide adequate electrical connections between the IC and the package terminals. For example, devices that operate at microwave frequencies require large surface area conductors with precisely defined shapes and sizes to operate properly. These requirements arise from the inductance affects encountered at microwave frequencies. The wires used in wire bonding are fabricated in bulk at fixed diameters that typically range between 0.18 and 1.27 mm. To achieve the large surface area required for microwave devices, multiple wires are bonded between the metallization pattern on the IC and the package terminal, increasing the conductive surface area between the IC and the package terminals. However, since the wires are pre-fabricated to standard diameters, it is very difficult to precisely "tune" the total conductor surface area to the device operating frequency.
A prior alternative technique for microwave devices utilizes a metal "ribbon" between the metallization pattern on the IC and the package terminals. Like the wires described above, metal ribbons are manufactured in bulk at various fixed widths and thicknesses. To achieve a customized (tuned) connection between the IC and the package terminals, the metal ribbons must be tediously cut by hand (usually with an EXACTO.TM. knife) to the precise shape and size needed. The hand-cut conductors exhibit ragged edges which adversely affect the performance of the microwave device and lack consistency from assembly to assembly.